Waste streams from cruise ships come back into nature which negatively influences the environment. Research has shown that actions need to be taken to reduce climate change. Not only the government should take their responsibility, but also other businesses, like the cruise industry. The cruise industry is a growing business and cruise ships have an environmental impact. This study aims to contribute to the development of sustainable, circular cruise ships. Specifically, the gas, fluid, and solid waste streams. The final product is a roadmap, based on waste stream analyses, towards a set of targets and goals. This master thesis, examines which steps need to be taken, focusing on the three waste streams to make the transition towards circular cruise ships following the City-zen method to comply with the UN sustainable development goals. Three roadmaps are made, with three different levels of ambition; 1. Fully Circular, 2. Collaboration Ship & Land, and 3. Positive effect on the environment to find the best way to design a sustainable cruise ship. The research can be subdivided into four main sections, background information, waste stream analysis, master planning, and conclusions. These four main sections are all in relation to the case study, cruise ships from Royal Caribbean Ltd. A literature study is conducted to obtain the needed information. The results show that it is impossible to ensure that no waste enters the environment under the conditions made for the specific roadmaps. On this basis, a combination of the three roadmaps and their technical solutions is made to design the sustainable circular cruise ship. The final design for retrofit cruise ships and newly built cruise ships is not fully circular. The treated black and grey water and bilge water still contain pollutants that come back into the sea. However, the emissions from the gas stream are reduced or fully eliminated, more pollutants are removed from the black, grey and bilge water, pollutant by-products are recycled on land, heat is recovered and reused, clean products as biogas, biodiesel and struvite are produced, seawater as ballast water is not needed, and non-hazardous and hazardous waste is reduced, reused and recycled. These adjustments and additions should be added to prevent waste discharge into the environment. This research also shows that the same design principles and interventions used in cities and building complexes can also be implemented on cruise ships, like the New Stepped Strategy, Cradle to Cradle, material passport, plants, heat pumps, and the energy exchange principle. Further research is needed into technical systems to treat and prevent waste from entering the environment and into other criteria like cost, energy consumption, needed materials and emissions.